As per my understanding you want to add min and max data tips for multiple lines.
I will try to explain it for a single line plot using an example below
x = linspace(1,10,10);
y = 2.*x;
[max_val,maxindex] = max(y);
[min_val,minindex]=min(y);
h =figure; hPlot = plot(x,y);
cursorMode = datacursormode(h);
MaxDatatip = cursorMode.createDatatip(hPlot);
MinDatatip= cursorMode.createDatatip(hPlot);
maxpos = [x(maxindex) y(maxindex)];
minpos=[x(minindex) y(minindex) ];
set(MaxDatatip, 'Position', maxpos)
set(MinDatatip, 'Position', minpos)
updateDataCursors(cursorMode);
For any further information you can go through the link
